append child react

showResult = (result) => {
    let node = document.createElement('DIV');
    node.classList.add('custom-alert');
    let textnode = document.createTextNode(result);
    node.appendChild(textnode);
    node.style.overflow = 'scroll';
    node.style.position = 'fixed';
    node.style.height = '5%';
    node.style.width = '100%';
    node.style.zIndex = '1000011111111';
    node.style.backgroundColor = 'wheat';
    node.style.wordBreak = 'break-all';
    node.style.padding = '20px';
    node.style.whiteSpace = 'pre-wrap';
    document.getElementById('app').appendChild(node);
};